DerekS

I care about MPG, but only loosely...it's a habit I picked up in my Honda CRZ years, where the fun was in hypermiling.

systemr

its very artificial, way too consistent. also if you are very lightly on the throttle and let off it pops

ipse dixit

Just wait until you get into an F-Type.

Like a video game. Makes the Rice Krispies cereal sound like a mime at work.

STG

PSE >> 991.2 = Party is over

cajerseyboy

One of the pleasures of PDK is the downshift with PSE on. ADDICTIVE!

DrCGuerra

I thought we were kindred spirits but I guess we are Ying and Yang.

Vise

You should hear it with an aftermarket x-pipe! The over run pops + crackle on downshift with my Cargraphic x-pipe is maniacal to say the least.

STG

I can imagine. Ever look into the Cargraphic 200cel headers?

subshooter

Yes. This is why the ECU needs to be updated when PSE is retrofitted.

petee1997

[QUOTE=NA430GTS;13119880]One of the pleasures of PDK is the downshift with PSE on. ADDICTIVE![/Q

Wrong quote, my mistake.

petee1997

Not true.

CSK 911 C4S

I drove the new car today and OMG the PSE sounds great.

The 991.2 PSE has to be one octave lower at idle than the 991.1 PSE and the crackle and pop is just as wonderful.

And the new engine is soooooooooo smoooth.

fast1

What Porsche is doing with PSE is replicating the exhaust sound that you have with a high revving race car's engine. The engine's performance must be maximized near redline since that is where it will be spending a significant amount of time, as opposed to a car designed for the street where it's rare that it goes to redline.

So how is this maximum performance at redline achieved? During the power stroke, it is necessary to open the exhaust valve before the piston gets to the bottom of the cylinder. This will allow the excess pressure in the cylinder to escape just before the piston reaches the bottom of the stroke. The term "Blow Down" is used to describe this event.

Timing the exhaust valve in this manner assures no pressure is left in the cylinder to push against the piston on the exhaust stroke. Otherwise, there could be significant pressure pushing against the piston as it starts up the cylinder. This would require some of the engine's power just to push the exhaust out of the cylinder, thereby reducing its power output to the wheels.

As to how Porsche achieves this sound is just speculation on my part, but the easiest way would be to program the ECU in such way that a spark plug wouldn't fire under certain conditions, thereby allowing some un-burnt fuel to flow out to the hot exhaust. This of course would cause a popping sound not unlike the sound that a race car engine makes at lower rpms when un-burnt fuel vents out to the exhaust. Since this event occurs in milliseconds, I doubt that there would be any measurable decrease in the car's MPG.

chuckbdc

The pops are about the same. Its the exhaust sound that is deeper pitched, sort of like the old air cooled 911s.

CSK 911 C4S